This section provides background information related to the present disclosure, which is not necessarily prior art.
Motor vehicle heating, ventilation, and air cooling (HVAC) systems typically include an HVAC casing with an evaporator and a heater core housed therein. The casing defines a defrost manifold, which includes a windshield outlet, a left side window outlet, and a right side window outlet. Heated airflow passing through the windshield outlet is directed to a windshield of the vehicle in order to defrost the windshield. Heated airflow passing through the left side window outlet is directed to a left side window of the vehicle in order to demist the left side window. Heated airflow passing through the right side window outlet is directed to a right side window in order to demist the right side window.
One or more control doors are included within the casing to regulate airflow through the defrost manifold. While current HVAC systems are able to suitably control airflow through the defrost manifold to the windshield and the side windows, enhanced airflow control would be desirable. For example, with current HVAC systems it is often the case that in full defrost mode too much demist is directed to the side windows; and in foot heating mode not enough demist is directed to the side windows or too much defrost is directed to the windshield. The present teachings advantageously provide for improved control of airflow through an HVAC case defrost manifold using a single control door, which simplifies manufacturing and operation, and reduces the overall cost of the HVAC system.